A track chain to be assembled using the jig according to this invention is partly denoted at 4 in FIG. 1 and FIG. 2. FIG. 3 depicts the joint portion of the track chain 4. A pair of preceding links 1' and a pair of following links 1 are joined together by a track joint 5 by fitting a bushing 3 on a track pin 2, whereby a desired length of track chain 4 can be assembled.
In FIG. 1 and FIG. 2 there is shown a track press 6 as the means employed in the abovementioned assembly. The way of assembling by using this track press 6 will be schematically explained hereinafter.
FIG. 1 shows the state of track press 6 before it is started into operation, wherein the forward (upper in the drawing) portion of the track chain 4 has already been joined together with links 1' by means of a track joint 5'. Hereat, a track joint 5 is carried by a rearward (lower in the drawing) jaw 7', a pair of following links 1 are attached to a pair of pin adapters 9 and a pair of bushing adapters 10 as shown with chain lines in FIG. 1 and with a partly enlarged section in FIG. 4, said links 1 are urged from the right and left sides and advanced toward the track joints 5 and 5' so as to be jointed as shown FIG. 2 and FIG. 5, and then respective adapters are retreated again to the position as shown in FIG. 1.
Particulars of respective adapters 9 and 10 are given in FIG. 4 and FIG. 5. As can be seen therefrom, adapters 9 and 10 include respectively outer cylinders 15 and 16 which have fixed, to their bottom surfaces, threaded rods 13 and 14 screwed in threaded holes 11 and 12 provided in a tool bar 8 referred to afterwards, and open in the direction opposite to said bottom surfaces. In the bores of the hollow outer cylinders 15 and 16 there are slidably fitted inner cylinders 17 and 18 respectively, and said inner cylinders 17 and 18 are always biased by springs 19 and 20 so as to protrude outwards, the springs 19 and 20 resiliently engaging the interior surfaces of the rear walls of the outer cylinders and the inner cylinders. Reference numerals 21 and 22 denote stopper screws that are screwed in transverse threaded holes in the peripheral walls of outer cylinders 15 and 16. The fore ends of said screws are fitted in grooves or slits 23 and 24 formed axially in the outer periphery of inner cylinders 17 and 18 to prevent the inner cylinders 17 and 18 from protruding all the way out of the outer cylinders 15 and 16 so that the sliding of the inner cylinders 17, 18 is limited between forwardmost and rearwardmost positions.
According to the size of the construction equipment to which the track chain 4 is attached, the track pin and link used therein will vary in length, and as a matter of course the distance between the track joints and the distance between respective links will also vary. In the case like this, it will be necessary for the above mentioned assembling device to change the positions of jaws 7 and 7', exchange adapters 9 and 10, further change the distance between adapters 9 and 10, and still further change the moving strokes of said adapters.
In order to change the distance between adapters 9 and 10 in the above mentioned assembling device, this applicant has improved said tool bar previously. The thus improved tool bar 8 is shown in FIG. 6A and FIG. 6B. FIGS. 6A and 6B show the surface and the back of tool bar 8 respectively. This tool bar 8 is provided at the central part with a long hole 27 for attaching the tool bar 8 to a base bed 25 of the track press 6 by means of a bolt 26. Reference numerals 28 and 29 denote small holes in which locating pins (not shown) between the tool bar 8 and the bed 25 are fitted. Threaded holes 11 and 12 are plural in number respectively and take the form of blank threaded holes arranged symmetrically with a long hole 27 as the center. The back surface is provided with plural blank threaded holes 11' and 12' which are located in positions different from those of the threaded holes 11 and 12 provided in the surface but serve for the same purposes.
Changing of the position between adapters 9 and 10 by means of the tool bar 8 of this type is effected in a manner of screwing the threaded rods 13 and 14 of the adapters 9 and 10 in the desired threaded holes 11 and 12. If the predetermined object is not still achieved, the tool bar 8 will be turned over, attached to the base bed 25 and screwed in the desired threaded holes 11' and 12'.
However, the above mentioned device is defective in that since the end opening (openings) of outer cylinder 15 and/or 16 presses on the side end faces of links 1 and 1' at every assembling operation during a long period of usage, the end face of the end opening is crushed, its inner peripheral flange is deformed so as to expand inwards, and thus the inner cylinders 17 and 18 are pressed in the inside of outer cylinders 15 and 16, whereby it becomes impossible for the inner cylinders to move for protruding from the end openings of the outer cylinders.
It is generally said that at the time of assembling (FIG. 2 and FIG. 5), by regulating the insertion distances of inner cylinders 17 and 18 against outer cylinders 15 and 16 to l and L (FIG. 5), the length l (FIG. 3) of the protrudent portion of the track pin 2 from links 1 and 1' can be held constant. However, the above mentioned device is further defective in that it is impossible to compensate the changed insertion distance as outer cylinders and/or inner cylinders wear due to usage and consequently it becomes impossible to hold the length l of the protrudent portion of the pin 2 constant, and that in order to remedy this undersirable state it is necessary to exchange adapters 9 and 10 each time and the assembling operation is retarded due to this exchanging operation.
The above mentioned device is still further defective in that, considering the distances of the opening end surfaces of outer cylinders 15 and 16 from the fitting surface of the tool bar 8, as said opening end surfaces wear due to usage, said distances are shortened so as to result in various disadvantages. Especially, when the degree of wear is unbalanced between those opening end surfaces, due to a long period of usage, links 1 and 1', which support the portion extending from the outer cylinder 16 to the outer cylinder 15, incline gradually so that it becomes impossible to attach the links 1 and 1' at right angles relative to the pin 2 and bushing 3, and in order to remedy this undesirable state it is necessary to exchange adapters 9 and 10 each time, and the assembling operation is retarded due to this exchanging operation. This phenomenon can be observed when re-assembling using the links 1 and 1' after they have been used to some extent. The reason is that when links 1 and 1' are used, they wear markedly at the side end surfaces of the portions supported by the adapter 9 (which are exposed always during use and so liable to wear) more than at the side end surfaces of the portions supported by the adapter 10, and accordingly when re-assembling using these links, the re-assembled body as a whole comes to be supported slantedly by the adapters 9 and 10 in the exactly same manner as mentioned above.
In addition thereto, the above mentioned device involves the following defects. In order to join the outer cylinders 15 and 16 rigidly to the tool bar 8 it is necessary to screw the rods 13 and 14 fully in the threaded holes 11 and 12 respectively, and therefore the locations of outer cylinders 15 and 16 in the peripheral direction relative to the tool bar 8 are always constant. On the other hand, in the joint portion shown in FIG. 3, the side end surface of the link 1 wears slantwise, for instance, as shown with a dotted line d in the left side of FIG. 3, owing to the long period of usage. When breaking up the thus slantly worn ones and using them for re-assembling the links 1 and 1', the slantly worn side end surfaces come to contact with the end surfaces of the outer cylinders 15 and 16. As the locations of outer cylinders 15 and 16 at this time are constant as aforesaid, said contact results in slant wear and deformation of the end surfaces of outer cylinders 15 and 16, too. In order to remedy this undesirable state, it is required to remove the adapters 9 and 10 from the tool bar 8 each time for evening the end surfaces of outer cylinders 15 and 16 by lathe turning or the like and to discontinue the track link assembling operation during said lathe turning operation, whereby the assembling efficiency is reduced.